Photocopying apparatus on the diffusion principle



June 1967 G. SCHWIENBACHER 3,327,602

PHOTOCOPYING APPARATUS ON -THE DIFFUSION PRINCIPLE I Filed Nov. 18, 1964 United States Patent 3,327,602 PHOTOCOPYING APPARATUS ON THE DIFFUSION PRINCIPLE Georges Schwienbacher, Forsterstrasse 64, Zurich, Switzerland Filed Nov. 18, 1964, Ser. No. 412,021 Claims priority, application Switzerland, Nov. 19, 1963, 14,215/ 63 9 Claims. (Cl. 95-75) My invention relates to apparatus for producing photocopies by the dilfusion method.

Such apparatus of heretofore known construction is capable of automatically separating the original from the negative sheet after exposure. The separation is effected mechanically by movable parts in the apparatus, for example by mechanical switching devices. Such switching devices are susceptible to trouble and have the disadvantage that the negative paper sheet must be arranged in displaced relation to the original of which the photocopy is to be made, or to a guiding foil relative to the paper feeding direction. If the negative paper is not so displaced relative to the original, no proper separation of the negative from the original is obtained. Another disadvantage is that the positive sheet, the negative sheet and the original document must be simultaneously slid into the machine.

Presently available photocopy machines operate with developing solutions in containers or pans having a volume of 500 to 2000 cc. According to British Patent No. 805,639, these solutions can be sucked into a reserve container when the apparatus is not in use. However, it remains disadvantageous, in that the developing baths are open to the ambient air and the entire developer solution is exposed to the carbon dioxide of the air and thus will oxidize. Furthermore, it is very unwieldy to connect reserve containers by plastic hoses to the apparatus for oifice use, particularly since photographic developing solutions have etching properties.

Another considerable disadvantage is that the entire amount of developing solution is used up chemically due to the copying, so that the developer gradually deteriorates in operational qualities which causes corresponding impairment in the quality of the copies made. If the copying appartus is not employed for a prolonged period of time, the solutions remaining from previous use are oxidized and deteriorated to such an extent that they must be replaced before placing the apparatus in operation again. For the same reason, it is often necessary first to clean the developer container in the machine.

Consequently, the presently available photocopying machines operating on the diffusion principle are not always available in condition for operation, which appears to be one of the main reasons for the current preference for dry copying methods or permanently operational machines operating by semi-moist methods, such as electrostats.

It is accordingly an object of my invention to avoid or greatly minimize the aforementioned shortcomings heretofore encountered with photocopying apparatus operating on the diffusion principle.

Another, more specific object of my invention is to provide a diffusion-type copying machine which does not possess open chemical baths, does not require any particular cleaning expedients, nor especially intricate manipulation, and which is nevertheless simple to operate and is always in operative condition.

A further object of my invention is to provide a diffusion-type photocopying apparatus capable of producing photocopies fully automatically within 3 to 4 seconds, inclusive of the time required for exposure and development.

Other features which are considered as characteristic for the invention are set forth in the appended claims.

Although the invention is illustrated and described herein as embodied in a photocopying apparatus on the diffusion principle, it is nevertheless .not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.

The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 is a partly diagrammatic sectional view of a photocopying apparatus constructed in accordance with my invention;

FIG. 2 is an edgewise View of a guiding foil arranged with an original sheet for copying, preparatory to the insertion thereof in the apparatus of FIG. 1;

FIG. 3 is an enlarged fragmentary view of FIG, 1 showing the photocopying apparatus in a more advanced stage of operation;

FIG. 4 is a modified fragmentary view of FIG. 1 including automatic means for dispensing developing fluid from the cartridge; and

FIG. 5 is a sectional view of a switch mechanism for actuating the automatic dispensing means of FIG. 4.

Referring now to the drawings and first particularly to FIG. 1, there is shown a photocopying apparatus having a housing 1. A holder 3 for sheets of positive paper is located at the top of the housing 1. A paper guide 8 pivotable on a pair of lugs extending from the housing 1 (only one lug shown in FIG. 1) keeps the upper end of the positive paper straight. When not in use, the guide 8 can be pivoted so that it lies close against the top wall of the housing 1. A tiltable lever 4, rotatable about a horizontal pivot 4' secured to a side wall of the housing 1, cooperates with the holder 3 for feeding sheets of positive paper between rollers 9 and 10 as described hereinafter in greater detail.

An inlet opening 31 is provided at the left hand side of the housing 1 for inserting a guide foil 17, holding an original document 18 to be copied, and a sheet 20 of negative paper placed beneath the same. A guide plate 32 extends through the opening 31 for guiding the foil, document and negative sheet package 17, 18, 20 to conventional exposure equipment 14 comprising a drum having a peripheral portion of transparent material and an interior fluorescent lamp (not shown). A conveyor belt arrangement 33 advances the package 17, 18, 20 around the upper surface of the exposure drum 14 and presses it against the drum 14 so as to limit relative movement between the negative sheet 20, the foil 17 and the original document 18.

An abutment plate 5 is fixedly mounted behind the exposure equipment 14 and cooperates with the curved leading portion 6 of the guiding foil 17 to thereby separate the guiding foil 17 and the original document 18 from the negative paper 20. The guiding foil and the original document retained therewith by the holder strip 19 as shown in FIG. 2 then abuts against the lever 4 and turns it clockwise about the pivot 4. The lever 4 has at its lower end a lug 30 which is moved out of the path of the positive paper 7 and thereby releases the positive paper 7 which now drops between the rollers 9 and 10. The two rollers press only lightly against the positive paper and feed it downward until the paper abuts against the fixed wall 13 where it is kept in position. The negative paper 20 is exposed as it passes over the cylindrical peripheral surface of the equipment 14 and is developed by the developing solution at 11. As described hereinabove, only a small quantity 16 of developing solution is previously injected into the apparatus, and this small quantity is collected and retained by capillary action at the locality 11, i.e. at the lowest point of the angular wall 13, and between the roller 10 and the wall portion 12. As the negative paper 20, wetted at 12 by the developing solution, abuts against the positive paper 7, it entrains the positive paper and passes it to the pinch roller 15 and then out of the apparatus through the opening 33. Meanwhile, the foil and original document are ejected through the opening at the top of the housing 1.

FIG. 2 shows the guiding foil 17 with the holder strip 19 consisting advantageously of a hard plastic such as hard polyvinyl chloride or the like and preformed with a curved leading edge portion 6 for guiding the original document 18 during its travel.

FIG. 3 is a fragmentary enlarged view of the apparatus of FIG. 1 and shows a stage of operation of the apparatus in which the curved edge 6 f the guide foil 17, retaining a document to be copied, has pivoted the tiltable lever 4 in a clockwise direction by striking against the upper lever arm thereof. Consequently, the lug 30 at the lower end of the lever 4, which normally blocks the positive paper sheet 7 from passing through the holder 3, is moved away from the blocking position shown in FIG. 1 and the positive sheet 7 slides downwardly so that it is nipped between the rollers 9 and 10 and thrust against the wall 13. The negative paper 20 advanced through the developer bath 11 entrains the positive sheet 7 at the lower end thereof and bends it thereafter into a common direction of travel. The positive and negative papers then assume the dotted line positions 7 and 20", respectively, as shown in FIG. 3. An automatic adjustment of the length of the negative and positive papers is eifected by the loose pressure between the rollers 9 and 10, so that a displacement of the negative paper relative to the guiding foil does not cause any displacement of the positive paper.

The operation of the apparatus hereinbefore described is as follows: The positive paper is inserted from above into the illustrated apparatus. A slight pressure with the finger on the developer cartridge 2 releases approximately 1 cc. developer solution for the subsequent development of the negative paper. The original document is slid into the holder 19 of the guiding foil 17 and then covered with a sheet of negative paper and thereafter placed upside down into the inlet slot at the left of the illustrated apparatus. The apparatus then feeds the document and the negative together with the guiding foil automatically over the exposing equipment, the original document is automatically separated, the positive paper is automatically joined with the developed negative paper, then squeezed off by two pinch rollers and ultimately ejected at the right of the machine.

Automatic subsequent dispensing of developer solution from the cartridge 2 is able to be effected by the mechanism shown in FIG. 4. The housing 1 for this modification of the apparatus of FIG. 1 has a pocket or recess 21 for retaining the cartridge 2. An electromagnetic or solenoid coil 22 with a tappet 23 located at the end of a plunger are mounted laterally to the recess 21. When the solenoid coil 22 is energized, the tappet 23 presses against the cartridge 2, which consists of thermoplastic material, for example, so that a necessary quantity of developer fluid for supplementing the bath 11 is squeezed out of the cartridge 2.

The switching mechanism shown in FIG. providing a modification of the apparatus of FIG. 1 is located adjacent the opening 31 of the housing 1 through which the guide foil 17 is inserted, i.e. the lower left-hand corner of FIG. 1, and serves to switch on the solenoid 22. The guide plate 32 extending through the inlet opening 31 is formed with a slot 24 at its inner end through which a double armed switch lever 25, when in the rest position 25' shown in phantom, extends into the path of the foil 4 17. The switch lever 25 is pivoted clockwise by the insertion of the foil 17 so that the lower arm of the lever 25, as viewed in FIG. 5, presses against the switch pin 27 of a microswitch 28 for energizing the coil 22 against the opposing bias of a weak tension spring 26.

I claim:

1. Diffusion-type photocopying apparatus comprising exposure means, means for conveying a guiding foil, holding an original document to be photocopied, together with a negative sheet in matching registry with the original document along a given path through said exposure means for forming a latent image of the original document on the negative sheet, said guiding foil having a leading edge portion with an upwardly curved shape, abutment means located downstream of said exposure means and en-gageable by said curved leading edge portion for diverting said foil and original document from said given path whereby only the negative sheet continues on said given path, developer means located further along said given path and traversible by the negative sheet for wetting the negative sheet with a developing solution, and means downstream of said developer means for placing a positive sheet in registered contact with the negative sheet so that the image of the original document is transferred from the negative sheet to the positive sheet.

2. Diffusion-type photocopying apparatus comprising exposure means, means for conveying a guiding foil, hol-ding an original document to be photocopied, together with a negative sheet in matching registry with the original document along a given path through said exposure means for forming a latent image of the original document on the negative sheet, said guiding foil having a leading edge portion with an upwardly curved shape, abutment means located downstream of said exposure means and engageable by said curved leading edge portion for diverting said foil and original document from said given path whereby only the negative sheet continues on said given path, de-

veloper means located further along said given path and traversible by the negative sheet for wetting the negative sheet with a developing solution, and means downstream of said developer means for placing a positive sheet in registered contact with the negative sheet so that the image of the original document is transferred from the negative sheet to the positive sheet, said means downstream of said developer means being actuable by said guiding foil at a location downstream of said exposure means for releasing the positive sheet in said given path.

3. Diffusion-type photocopying apparatus comprising exposure means, means for conveying a guiding foil, holding an original document to be photocopied,together with a negative sheet in matching registry with the original document along a given path through said exposure means for forming a latent image of the original document on the negative sheet, said guiding foil having a leading edge portion with an upwardly curved shape, abutment means located downstream of said exposure means and engageable by said curved leading edge portion for diverting said foil and original document from said given path whereby only the negative sheet continues on said given path, developer means located further along said given path and traversible by the negative sheet for wetting the negative sheet with a developing solution, and positive sheet holder means including a movable member adjacent said abutment means and actuable by the diverted guiding foil for releasing a positive sheet into said given path downstream of said developer means so that it falls freely into registered contact with the negative sheet whereby the image of the original document is transferred from the negative sheet to the positive sheet.

4. Photocopying apparatus according to claim 1, wherein said developer means contains less than 50 cc. of developing solution.

5. Photocopying apparatus according to claim 1 including developing solution supply means adapted to supply to said developer means a quantity of developing solution sufficient for developing a single photocopy at a time.

6. Photocopying apparatus according to claim 5 including means actutable by said guidance foil for automatically supplying to said developer means said quantity of developing solution from said supply means.

7. Photocopying apparatus according to claim 5 wherein said supply means comprises a pressure cartridge of plastic material adapted to discharge said quantity of developing solution when squeezed.

8. Photocopying apparatus according to claim 7, wherein said means actua-ble by said guidance foil comprises a pivotable lever located in said given path'upstream of said exposure means and adapted to be pivoted by said guiding foil, and a switch located adjacent said lever and engageable thereby, when pivoted, for energizing a sole noid located adjacent said pressure cartridge, said solenoid having plunger means displaceable into pressure engagement with said cartridge when said solenoid is energized thereby said quantity of developing solution is automatically discharged from said cartridge.

9. Photocopying apparatus according to claim 3, wherein said movable member comprises a pivotable lever having a lug at one end normally in a position obstructing release of the positive sheet from said holder means, said lug being pivotable out of said obstructing position whereby the positive sheet is released.

References Cited UNITED STATES PATENTS 3/1962 Limberge-r 9575 5/1962 Moser 95-75 

1. DIFFUSION-TYPE PHOTOCOPYING APPARATUS COMPRISING EXPOSURE MEANS, MEANS FOR CONVEYING A GUIDING FOIL, HOLDING AN ORIGINAL DOCUMENT TO BE PHOTOCOPIED, TOGETHER WITH A NEGATIVE SHEET IN MATCHING REGISTRY WITH THE ORIGINAL DOCUMENT ALONG A GIVEN PATH THROUGH SAID EXPOSURE MEANS FOR FORMING A LATENT IMAGE OF THE ORIGINAL DOCUMENT ON THE NEGATIVE SHEET, SAID GUIDING FOIL HAVING A LEADING EDGE PORTION WITH AN UPWARDLY CURVED SHAPE, ABUTMENT MEANS LOCATED DOWNSTREAM OF SAID EXPOSURE MEANS AND ENGAGEABLE BY SAID CURVED LEADING EDGE PORTION FOR DIVERTING SAID FOIL AND ORIGINAL DOCUMENT FROM SAID GIVEN PATH WHEREBY ONLY THE NEGATIVE SHEET CONTINUES ON SAID GIVEN PATH, DEVELOPER MEANS LOCATED FURTHER ALONG SAID GIVEN PATH AND TRAVERSIBLE BY THE NEGATIVE SHEET FOR WETTING THE NEGATIVE SHEET WITH A DEVELOPING SOLUTION, AND MEANS DOWNSTREAM OF SAID DEVELOPER MEANS FOR PLACING A POSITIVE SHEET IN REGISTERED CONTACT WITH THE NEGATIVE SHEET SO THAT THE IMAGE OF THE ORIGINAL DOCUMENT IS TRANSFERRED FROM THE NEGATIVE SHEET TO THE POSITIVE SHEET. 